Manufacture of thiocarbanilide for vulcanization of caoutchouc



UNITED STATES PATENT OFFICE.

CLAYTON W. BEDFORD AND ROBERT L. SIIBLEY, OF AKRON, OHIO, ASSIG-NORS TO THE GOODYEAR TIRE & RUBBER COMPANY, OF AKRON, OHIO, A CORPORATION OF OHIO.

MANUFACTURE OF THIOCARIBANILIDE FOR VULCANIZATION OF CAOUTCHOUC.

No Drawing.

T 0 all whom it may concern:

Be it known that we, CLAYTON W. BED- FORD and ROBERT L. SIBLEY, citizens of the United States, residing at Akron, in the county of Summit and State of Ohio, have invented a new and useful Improvement in the Manufacture-of Thiocarbanilide for vulcanization of Caoutchouc, of which the following is a specification;

The present invention relates to the production of thiocarbanilide by a method peculiarly suitable for use in connection with the vulcanization of caoutchouc.

Thiocarbanilide, is well known to be a valuable commercial accelerator for expediting and improving the vulcanization of rubber. In the manufacture of thiocarbanilide from aniline and carbon bisulphide, hydrogen-sulphide is produced in large quantities, and various methods have been resorted to for removing it from the reaction mixture in order to speed the reaction and to ensure its completion. Sulphur, for example, appears to act as a catalyst and very materially shortens the time of the reaction. Litharge or other metallic oxides may be used which will react with the hydrogen sulphide to produce metallic sulphides and water. Pyridine may also be used, its basicproperties causing it to react with the acidic hydrogen-sulphide.

The present inventors have discovered a means by which the hydrogen-sulphide may be conveniently and expeditiously removed from the zone of the reaction, with all of the attendant advantages of this result, by the use of a compound present in the reaction zone and having a marked aflinity for the hydrogen-sulphide and reacting therewith to produce a substance which may be permitted to remain admixed with the thiocarbanilide, where the latter .is to be employed as. an accelerator in the vulcanization of caoutchouc.

These desirable results are attained by the use of a paranitroso body. such. for example, as paranitrosophenol, oi paranitrosodimethylaniline.

Example I. 186 grains aniline (2 molecules); 314% grams carbon bisulphide; 150 grains paranitroso-dimethyl aniline (1 molecule).

' proportion of carbon bisulphide is arri d at as follows: 76 grams (1 molecule) itr reaction with the aniline; 38

Specification of Letters Yatent.

' denser.

Patented Feb. 14, 1922.

Application filed August 12, 1918. Serial 110. 249,581.

grams (a molecule) for reaction with the base produced by the reaction of hydrogen sulphide with paranitroso-dimethyl aniline; 200 grams, excess for solvent action and temperature control.

The paranitroso-dimethyl-aniline and'carbon bisulphide are mixed, and the aniline is slowly added thereto under a reflux con- The liquid is maintained at the boiling point in order to prevent the accumulation of aniline with a periodic violent reaction.

When the entire quantity of aniline has been added, the heating is continued under a reflux for a few minutes, and the excess carbon bisulphide is then distilled off. The residue which consists of thiocarbanilide in admixture with the thiocarbanilide derivative formed by the reaction of hydrogen sulphide and carbon bisulphide on the paranitroso-dimethyl-aniline, in the presence of aniline, may be used without further purification for the vulcanization process, a small percentage being added to the rubber mix (for example, from one-half to two per cent), and vulcanization then carried out in the usual manner.

Example II. One or three mols of aniline (93 9:. or 2.79 g.) may be used instead of 186 g. as in example I, with the result that there will be obtained mixed thiocarbanilides of slightly different properties. Three mols of aniline is apparently the maximum which will be forced to react with CS by one mol of paranitroso-dimethyl-aniline. Paranitroso-dimethyl-aniline reacts with H 8 up to two mols under the above conditions, the final reaction corresponding to the following equation:

It is evident therefore that when using three mols of aniline it IS a better method to dissolve the nitroso body in and to run 1 it into warm aniline in order to have sufficient aniline present at all times to give a complete reaction.

ll here three molecules ployed. as in the toregoi action probably proceeds -i such a manner as to produce a amide di ietl l-aniline as an interinedi product. s

a auiiine are ear example. the rethen reacts with the aniline and carbon bisulphide present to form a mixture of symmetrical and unsymmetrical thio urea derivatives which we have found to be particularly valuable for the valcanizatiori of caoutchouc.

It will be apparent from the above that in the para-nitroso body named we have discovered a substance forming a highly desirable agent for expediting reversible reactions in which hydrogen sulphide is liberated, the aflinity of the nitroso body for the hydrogen sulphide being so great as to cause the reaction by which it is produced to pro ceed in the shortest time to the highest possible degree of completion. In the examples given a formation of 100% of thio carbanilide is easily attained, and the speed is limited'only to the physical-conditions of handling the material.

The nature of the reaction between paranitroso-dimethyl-aniline and hydrogen sulphide and of the reaction between this reaction product and carbon bisulphide, together with the nature and uses of the products are very fully described in our co-pending applications Serial No. 249,579, and 'Serial No. 249,580, both filed of even date herewith. y

In the foregoing we have described in some detail three procedures in accordance with our invention, but it is to be understood that this is illustrative only and that the invention is neither limited to the examples given, nor dependent upon the accuracy of the theories which we have advanced by way of ex planation, except in so far as such limitations form a part of the appended claims, in which it is our intention to claim all novelty inherent in our invention as broadly as is permissible, in view of the prior art.

What we claim is:

1. In the vulcanization of caoutchouc, the process which consists in incorporating into the caoutchouc mix a small percentage of a mixture of substituted thioureas, and heatin the mass with a vulcanizing agent to e ect vulcanization.

2. In the vulcanization of caoutchouc, the process which consists in incorporating into the caoutchouc mix a small percentage of an unsymmetrical substituted thiourea, and heating the mass with a vulcanizing agent to effect vulcanization.

3. In the vulcanization of caoutchouc, the process which consists in incorporating into the caoutchouc mix a small percentage of an unsymmetrical substituted thiourea produced by the reaction of carbon bisulphide on a mixture of a plurality of amido compounds, and heating the mass with a vulcanizing agent to effect vulcanization.

4. In the vulcanization of caoutchouc, the process which consists in incorporating into the caoutchouc mix a small percentage of the substituted thioureas produced by the reaction of carbon bisulphide on a mixture of a plurality of amido compounds, and heating the mass with a vulcanizing agent to effect vulcanization.

5. In the vulcanization of caoutchouc, the process which consists in incorporating into the caoutchouc mix a small percentage of the substituted thioureas produced by the reaction of a mixture of para amido dimethylaniline, and aniline with carbon bisulphide, and heating with a vulcanizing agent to effect vulcanization.

6. In the art of vulcanizing caoutchouc, the process which consists in incorporating into the caoutchouc mix the mixture of thioureas produced by the reaction of aniline and carbon bisulphide in the presence of paranitroso-dimethyl-aniline, and heatin the same with a vulcanizing agent to effect vulcanization.

7. In the art of vulcanizing caoutchouc, the process which consists in incorporating into the caoutchouc mix the mixture of substituted thioureas produced by the reaction between a primary aromatic amine and carbon bisulphide in the presence of a paranitroso body and heating the same with a vulcanizing agent to effect vulcanization.

CLAYTON IV. BEDFORD. ROBERT L. SIBLEY. 

